Though it's not as official as in China, major American social networks are increasingly heavily moderated, and increasingly do work closely with govt and close-to-government entities to enact desired moderation (censorship, if you prefer) policies.

They do this "voluntarily", but it's not clear they could actually decline w/o suffering consequences.

This is perhaps somewhat less true at Twitter post-Elon aquisition. It will be interesting to see how it plays out.